1. Field of the Invention
The invention relates to a method for the treatment of fly ash from a combustion process in a waste incineration plant, of in particular domestic waste, whereby fly ash is separated from the combustion process. Furthermore, the invention relates to a process for the operation of a waste incineration plant, in particular for the incineration of municipal solid waste or the like.
2. Description of Related Art
In waste incineration facilities for municipal solid waste bottom ash (grate dumpings and grate riddlings), boiler fly ash in the drafts of the boiler and filter fly ash in the flue gas treatment accrue as solid residues. These residues of the combustion process contain materials that can impair their recyclability. These contaminants can, for example, be unburned carbon compounds, soluble metals and their compounds, halogenated hydrocarbons such as dioxins, furans, and their precursors.
The best available techniques for waste incineration facilities are, for example, documented in the “Reference Document on the Best Available Techniques for Waste Incineration” by the European Commission, General Directorate, Joint Research Centre (JRC), Institute for Prospective Technological Studies, published August 2006.
Furthermore the treatment of residues of waste incineration, for example the treatment of bottom ash/waste incineration bottom ash with the best available techniques today is described in the “Reference Document on the best Available Techniques for Waste Treatment Industries”, published by the European Commission, August 2006.
In addition, DE 10 2007 057 106 A1 discloses a process for the production of compactable granule of bottom ash as a product of waste incineration.
In modern waste incineration facilities, the bottom ash after mechanical treatment can be applied as a waste for re-use to replace mineral wastes preferably in road construction as drainage or sub base as long as the environmental and construction requirements are fulfilled. For example, ferrous metals and non-ferrous metals such as aluminium or copper, recovered from the waste incineration process are recycled in steel works or metallurgical plants respectively.
In the current waste incineration processes there is typically also produced waste which is dangerous for the environment, which has to be disposed in licensed landfills, wherein this waste for the landfills is obtained as mixture of fly ashes and residues of the exhaust gas purification in the amount of about 6 weight % to 8 weight % of the waste treated. Hereby, the amount of the hazardous waste to be disposed depends on the type of flue gas treatment and the emission limits for fly ashes, in particular boiler fly ash and filter fly ash.
Furthermore, another important aspect of thermal waste treatment respectively incineration of municipal waste or residential waste or the like in existing waste incineration facilities is the recovery of usable energy to improve the energy balance and in addition to reduce climate relevant gases besides the recovery of re-usable materials. The recovery of re-usable byproducts reduces (marginally) the effectiveness of the production of usable energy by thermal waste treatment.
Starting from this state of the art, the object of the invention is to reduce the amount of residues produced in the process of thermal waste treatment that have to be disposed in landfills, wherein it should be possible to gain an increased rate of re-usable materials.